TR2/3/3A HVDA Speedometer Drive

[mastaphixa]

My 58 TR3a has an HVDA transmission fitted. My speedometer needle bounces all over the place when hooked to the transmission. I use a Toyota 90 degree adapter and the HVDA speedometer cable that came in the kit. My speedometer was mechanically overhauled by West Valley Instruments. Trouble shooting this problem I removed the 90 degree adapter from the transmission and the speedometer cable from the 90 adapter and spun the cable drive with my battery drill. The needle moved smoothly and to what ever speed I desired by modulating the drill speed, no bouncing at all. I then reattached the 90 adapter and did the same, once again the needle was steady as a rock at what ever speed I wanted. I was really surprised at this result. To me it clears the instrument, the speedo cable and the 90 degree adapter, but that only leaves an issue with the speedo drive gear in the transmission. Has anyone else experienced this? If I pull the speedo drive gear out of the gearbox will it dump the lube?

 

[bammons]

I don't have a answer but will be watching this. My speedo seemed to "slow" down above 60MPH and then just quit altogether. I thought it was the cable (HVDA setup) but I unhitched it from the speedo and it still turned when I drove it so it must be the speedo (prior to the restoration it worked fine). I did not use the 90* adapter. While it worked it was bouncy. Bruce

 

[charleyf]

I believe that there is a seal as a part of the internal part of the speedo drive. So I would guess that you could drip some oil. Maybe you could elevate the rear of the car to push the oil to the front.
Do you have any sharp bends in the cable? You might try some additional light lube into the cable housing. I have always been concerned about the amount of heat the angle drive and cable get sitting directly above the exhaust pipe.
Actually I have had a lot of problems with the 90 degree drives. There are two types. One that is simply a short piece of cable within the housing and the second that has actual gears. I went through two of the cable types. But I got my drives off of junked cars when I found the trannies.
Charley

 

[mastaphixa]

I believe that there is a seal as a part of the internal part of the speedo drive. So I would guess that you could drip some oil. Maybe you could elevate the rear of the car to push the oil to the front.
Do you have any sharp bends in the cable? You might try some additional light lube into the cable housing. I have always been concerned about the amount of heat the angle drive and cable get sitting directly above the exhaust pipe.
Actually I have had a lot of problems with the 90 degree drives. There are two types. One that is simply a short piece of cable within the housing and the second that has actual gears. I went through two of the cable types. But I got my drives off of junked cars when I found the trannies.
Charley

Where did you source the gear type 90 drive? I share your concern about the heat.

 

[charleyf]

Off of a junked Toyota. A number of years ago. It is still working. I went through the whole inventory at a PICK & PULL. Crawling under each suspect Toyota. Sorry I can not be any more specific.
Charley

 

[mctriumph]

Guys, once and for all , you do NOT need the angle drive at all. There is room for the cable to fit
between the frame rail and the floor. I have personally done this on all the cars after installing
my Eaglegate conversion.
The problem as described is lubrication /long cable syndrome. All my new cables get lubed before
they are shipped .
Mad dog

 

[bammons]

I ran my cable over the transmission and did not use the 90* drive but since I posted I saw that my cable end at the transmission was shredded and found a "kink" that probably caused the shredding. How are the rest of you routing the cable? Bruce

 

[mastaphixa]

MadDog, I understand your routing and will probably go that direction as I work on the passenger floor pan this winter. However, as stated in my original post, I have driven the existing cable set up with a battery drill and the speedo works beautifully leading me to wonder if there is a problem with the speedo drive gear in the gearbox. Believe me, I fully expected the 90 degree drive to be the culprit here and was surprised when it wasn't.

 

[mctriumph]

Bounce is often due to temperature /lube issues. Cold can cause old lube to make the cable
do strange things. This is also true of the escapement in the speedo its self. IMHO these old
technology gages have likely always had "issues", even from new.
Mad dog

 

[mastaphixa]

To close the loop on this item, I replaced the speedo drive gear in the transmission. The gear had damage to the plastic gear teeth. Not sure how that happened but after I replaced the drive gear my speedo is pretty calm now. Reads a bit low, but at least it isn't waving at me in semi fore.

 

[mctriumph]

Ah Ha , unusual to see this gear fail but plastic is what it is.
My 3b is coming along, got the rear wings set back on permanently yesterday. the front wings
will be done by the end of the week which will complete the bodywork (happy happy joy joy)
Mad dog